You can check the Defensive and Offensive Strength of your army – and that of the other Commanders in your Alliance (if you have permission) – from the “Statistics” section in the "My Alliance" tab of the Alliance Center.
Please be aware that the values shown on this screen do not always accurately reflect those displayed elsewhere in the game, or indeed the current actual power of a given army.
Discrepancies occur because Alliance Center statistics are only updated once every 3 hours. Recent Battles and acquisitions will not be included, and recently expired bonuses may not be factored into your total. Statistics may also change depending on which Nanochips are active, and on whether your Elite Status is active.
It should also be noted that the bonus your army derives from its Strategic Units is calculated at the moment when the Battle occurs. Your army's Strength may vary depending on the Supporting Units that are deployed alongside the Strategic ones.
In the “Statistics” window, the increase/decrease statistic compares the current overall Offensive and Defensive Strength of your Units to their overall Offensive and Defensive Strength on the Saturday of the previous week.